Solid-state light sources are used in a number of well-known video applications, including video projectors and rear-projection television systems. Common solid-state light sources include semiconductor edge-emitting laser diodes (LDs), vertical cavity surface-emitting laser diodes (VCSELs), diode pumped solid-state frequency doubled (DPSSFD) lasers, and light-emitting diodes (LEDs), among others. Laser-based and LED-based video projectors have been used extensively in business environments and have recently come into wide use in large-screen projection systems in home theaters.
Various laser-based and LED-based projection systems are described in U.S. Pat. Nos. 7,244,032 (Inamoto), 7,252,394 (Fu), 7,255,445 (Kojima), 7,304,795 (Yavid), and 7,355,657 (Chilla). The disclosures of U.S. Pat. Nos. 7,244,032, 7,252,394, 7,255,445, 7,304,795, and 7,355,657 are hereby incorporated by reference into the present disclosure as if fully set forth herein.
The miniaturization of projection systems has led to the development of so-called “pico-projectors” that may be embedded in other systems or may be implemented as stand-alone devices. Stand-alone devices include, by way of example, pocket or ultra-mobile projectors that maybe be powered from a battery or an external power source and have a wide range of input options. Embedded applications include, for example, mobile phones and heads-up displays for vehicle dashboards.
An exemplary pico-projector system is the PicoP™ projector engine developed by Microvision, Inc., which has a form factor suitable for implementation in a mobile phone, a vehicle heads-up display (HUD), and other hand-held portable device. The PicoP engine includes RGB laser sources, a micro-electro-mechanical system (MEMS) scanning mirror, optics and video processing electronics for receiving video data from a source and generating an image to be projected on any desired surface (e.g., screen, wall, paper, chair back, etc.). Another exemplary pico-projection system is the Necsel™ projector developed by Novalux, Inc.
However, pico-projection systems face a number of technical problems that are not as critical in larger projection systems, such as table-top projectors, rear-projection televisions, and home theatre projection systems. One of the chief technical problems is power reduction, since many pico-projectors operate mostly or even exclusively on battery power. Advantageously, power reduction also reduces the heat produced by the projector.
Cost reduction is also significant, particularly in embedded systems. For example, the total price of a mobile phone, including the embedded pico-projector, may be effectively limited by consumer demand to a few hundred dollars. Thus, the cost of the pico-projector components must be a fraction of the cost of the projector components of, for example, a rear-projection television.
Therefore, there is a need in the art for pico-projection systems that are ultra-compact, operate at reduced power, and produce less heat. There is also a need for pico-projection systems that cost less and provide enhanced capabilities to a host system, such as a mobile phone.